The present invention relates to chewing gum. More specifically, this invention relates to improved formulations for chewing gum bases and chewing gum containing a polyolefin thermoplastic elastomer.
Primary components of a chewing gum typically are a water-insoluble gum base portion and a water-soluble bulking agent portion typically including a bulking agent (such as a sugar or sugar alcohol) together with minor amounts of secondary components such as flavors, colorants, water-soluble softeners, gum emulsifiers, acidulants and sensates. Typically, the water-soluble portion, sensates, and flavors dissipate during chewing and the gum base is retained in the mouth throughout the chew.
Water-insoluble gum base typically includes elastomers, elastomer plasticizers, softeners/emulsifiers including fats and oils, and fillers. Elastomers useful gum bases typically are synthetic elastomers such as polyisobutylene, isobutylene-isoprene copolymers (“butyl rubber”), styrene-butadiene copolymers, polyisoprene, and combinations thereof. Also, natural elastomers such as natural rubbers can be used.
Because the elastomer component of a gum base is a significant portion of a gum formulation, the characteristics of such elastomer are important to the gum composition, especially regarding those properties important to consumer acceptance. Among properties important to consumers are odor, taste, chewing properties, and mouthfeel, including an ability of a gum composition to form a cud while chewing. Further, physical characteristics of the elastomer affect processibility of a gum base and a chewing gum formulation including a gum base.
The elastomer most widely used in chewing gum is butyl rubber based on consumer acceptance of chewing properties for a resulting chewing gum product and a lack of objectionable odor or taste associated with butyl rubber. Polyisobutylene (PIB) is another elastomer frequently used in gum bases. Lower molecular weight (below 100,000 viscosity average) PIB improves compatibility of base components, modifies elasticity and softens the chewing characteristics of gum bases to which it is added. However, it is not generally usable as a sole elastomer replacement in a gum base formulation. Higher molecular weight (at least 100,000 viscosity average) PIB acts more like butyl rubber, but its use is less common. Styrene butadiene copolymer rubber (SBR) has been described as useful as an elastomer in gum products.
Typically, gum base components are blended in a mechanical mixer to form a uniform mixture which may be formed into sheets, blocks or pellets for later incorporation into a chewing gum. Proper mixing is important to maintain a uniform and consistent composition, which is capable of being further formed into consumer-acceptable products. Such mixing typically requires input of heat and mechanical energy over a sufficient time to manufacture a suitable product. Gum base formulations which require less energy or mixing time to produce a suitable product would be advantageous in the art.
Prior to blending in a mixer, it is typically necessary to grind elastomers such as natural rubbers, butyl rubber, SBR and higher molecular weight polyisobutylene into a course particulate. The grinding typically is carried out with addition of a filler, such as calcium carbonate or talc, to prevent agglomeration of the freshly ground elastomer. Often it is necessary to chill the elastomer before grinding or even to chill the grinding apparatus to enhance grinding efficiency and further reduce agglomeration. Even with these measures, it is usually necessary to carry out the grinding process within a few hours to a few days before the gum base mixing operation to prevent agglomeration of the ground elastomer. The entire grinding process is time and energy consuming and it reduces the flexibility of production scheduling. In a variation, it is possible to grind the elastomer in the mixer prior to commencement of the blending operation. However, this requires a more powerful mixer than would otherwise be necessary and it is generally inefficient and adds considerably to the total mixing time.
This invention is directed to a gum base and a consumer-acceptable chewing gum formulation containing such gum base which typically requires less mixing energy or time.